A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
Increasing demands on throughput of the lithographic apparatus, e.g. on an amount of substrates to be processed by the lithographic apparatus in a certain time period, require increasing speeds and accelerations of stages such as a substrate table or a patterning device (e.g., mask) table. Furthermore, demands on resolution and accuracy of the pattern to be projected by the lithographic apparatus onto the substrate increase, which translates into a tendency to increase a size of the patterning device, in combination with an increased demagnification factor of the projection optics, to be able to provide the required level of detail on the substrate. On the one hand, requirements as to a high scanning speed lead to keeping a weight of a stage as low as possible, while on the other hand, the stage should be constructed such as to obtain a high stiffness, to avoid occurrence or excitation of resonance modes of the stage, such high stiffness tending to result in massive stage construction. Even further, to be able to achieve a high internal stiffness, use is made of materials having a high stiffness, which unfortunately have a small relative damping, resulting in long settling times for internal vibrations.